1. Field of the Invention
The present invention relates to an amorphous siliceous powder, a method for production thereof and a use thereof.
2. Related Art
With rising demand for environmental conservation in recent years, it has been desired to impart flame retardancy to semiconductor sealing materials used for sealing semiconductor elements without using harmful flame retardants such as antimony compounds and brominated epoxy resins which have considerable environmental impact, and impart heat resistance to lead-free solders containing no lead. Semiconductor sealing materials are mainly composed of epoxy resins, phenol resin curing agents, curing accelerators, inorganic fillers and the like, In order to satisfy the requirements described above, semiconductor sealing materials including epoxy resins and the phenol resins having structures with abundant aromatic rings, and which are high flame retardant and heat resistant, and high inorganic filler loading have been employed. Thus, viscosity of the semiconductor sealing material upon sealing tends to increase.
Meanwhile, in response to demand for smaller, lighter and more sophisticated electronic devices, rapid development has been seen in thinning of electronic components, reducing the diameter of and lengthening spans of gold wire, and increasing the density of wiring pitch in an internal structure of a semiconductor. When a semiconductor is sealed using a semiconductor sealing material having a high viscosity, problems result, such as gold wire is deformed and cut, the semiconductor element is inclined, and narrow spaces are not filled. Thus, there is demand for a semiconductor sealing material that is flame retardant and which has reduced viscosity to allow correct sealing and reduce improper molding.
To satisfy these demands, semiconductor sealing materials having a reduced viscosity and enhanced molding property have been obtained by improving the epoxy resin and the phenol resin curing agent used therein (Patent Documents 1 and 2). Improvements in curing accelerators have been achieved with a technique referred to as ‘making a latent state’, where a reactive substrate is protected using a component which inhibits a curing property for the purpose of raising a temperature when curing of the epoxy resin is initiated (Patent Documents 3 and 4). Improvements in inorganic fillers have been achieved with controlling the particle size distribution thereof, such that the viscosity of the sealing material, which contains an inorganic filler, does not increase even at high inorganic filler loading (Patent Documents 5 and 6). However, these sealing materials do not have sufficiently reduced viscosity and enhanced molding property, and thus, prior to the present invention, no semiconductor sealing material having a reduced viscosity upon sealing with high inorganic filler loading, and enhanced molding property was available.    [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2007-231159    [Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2007-262385    [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2006-225630    [Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2002-284859    [Patent Document 5] Japanese Unexamined Patent Application, First Publication No. 2005-239892    [Patent Document 6] WO2007/132771